Abstract: A controller for a Hall effect sensor includes a sensor section including a Hall effect sensor with a hysteresis set in the output electric signal characteristic with respect to the magnetic flux density, a power supply section for supplying a source power to the Hall effect sensor, and a signal processor for processing a signal output from the sensor section. The power supply section supplies power with a voltage, which is varied cyclically in a predetermined range and is increased gradually, to the Hall effect sensor.

Abstract: A steering system for a boat propelling apparatus is disclosed, which includes an operation unit, a steering piston-and-cylinder assembly and an operating fluid switching unit. The operation unit causes a steering arm of a propelling unit to be operated with operation of a steering wheel installed in the boat. The steering piston-and-cylinder assembly is connected to an operating fluid supply pump and a drain tank and capable of being supplied with operating fluid. Its piston rod is coupled to the steering arm. The operating fluid switching unit is disposed between the steering piston-and-cylinder assembly on one hand and the operating fluid supply pump and the drain tank on the other hand, and it switches the flow of operating fluid with the operation of the operation unit. It includes a switching section having a poppet valve coupled to the operation unit. The operating fluid switching unit includes a switching section and a normally closed drain control section.